Many are being slowly drawn into the Asuryani camp, for the lure of an at least partially functional solution is strong, and some who have found themselves in perilous waters have begun drifting into the orbit of Ulthwe for survival. The emergence of your own faction in the northern rim, however, may give many of these a rallying-point, and the information you discovered on the nature of Aeldari souls and the Curses will likely cause a shakeup as previous seeming failures are reexamined and ideas now known to be unworkable are abandoned.
As expected, the Asuryani are in a very strong position on the grounds of "your souls are being eaten RIGHT NOW. If you don't want your souls eaten, this provably stops it" and frankly no one else has anything to offer that matches that.
Ulthwe is compelling to anyone who thinks they will die of other things before their souls get eaten, since their rallying cry is togetherness and mutual aid which will stop people from dying right now, but none of what they present are solutions to the problem that the Asuryani are solving. Or, well, "solving".
Our faction presenting our research will bring us a lot of credibility in that we can promise to solve these problems
eventually- but we don't have any immediate solution for
right now except to point at the Ishari and go "turning into plantpeople worked for them". And most people won't want to do what they did, so ultimately we're building our entire credibility on the promise of future solutions instead of on concrete offerings that give at least a partial solution right now.
Overall I think the Asuryani are going to keep growing, and fairly aggressively, because even the people who believe in us and want us to succeed- perhaps even to the point of backing us in alliance- aren't going to want to keep having their souls eaten while they wait. And we don't have anything that can stop this. Our best bet is probably to make friends with as many people as we can who are either in the Asuryani camp for pragmatic reasons or drifting that way, and ally with them on the logic of "even if you're doing what works now as a patch job, put your faith in us for a better more permanent solution later". Arguing that our two solutions are not opposed but rather addressing the problem on different timescales could avoid a lot of conflict and bring us long-term political stability and credibility.